When application programs or processes provide images or graphics to be displayed, the application programs or processes may send graphics commands to operating system components or other processes that use the graphics commands to render the images or graphics. The graphics commands, which are also referred to as higher-level graphics commands or primitives, might specify or define colors, lines, shapes, and other graphics constructs. The operating system components or processes receiving the graphics commands may interpret or convert the graphics commands into lower-level graphics information such as individual pixel values or bitmaps which are used to render graphics on a display device.
An example of graphics commands is GDI which represents “Graphical Device Interface”, “Graphics Device Interface”, or “Graphics Display Interface”. In a GDI implementation, an interface (i.e., GDI interface) may be part of or supports a component or process that receives the graphics commands. In particular, the GDI interface receives parameters from an application, where the parameters are for an image or graphic to be represented. The GDI interface produces the image by sending commands to a process or component which in turn renders the image to a display or output device such as a monitor, printer, etc.
In certain implementations, the application programs or processes sending such graphics commands reside on devices or computers that are separate from devices or computers hosting the operating system components or processes that receive the graphics commands. These implementations may be referred to as trans-machine systems, examples of which include terminal service systems where applications reside on a central server computer and remote client computers receive the graphics commands that are rendered locally (i.e., at the client computers). In other implementations, the application programs and operating system components (processes) receiving the graphics commands reside on the same device or computer and may be referred to as trans-process systems. Other implementations may send graphics commands using the same process; however, such implementations may use different threads in which the graphics commands are passed. These implementations may be referred to as trans-thread systems.
Regardless of the particular implementation or system, whether it be trans-machine, trans-process, or trans-thread, the graphics commands sent by the application programs are typically transitory. In other words, once the graphics commands are sent by the application for processing and received, they are immediately consumed or processed. This is particularly true where GDI is used, where the interface receives parameters, creates graphics commands, and the graphics commands are immediately consumed. Therefore, if a particular graphics or image is lost, the application program or process must resend the graphics commands (or parameters) to the receiving component or process. Furthermore, since graphics commands may be consumed as they are received, if a user desires to replicate the graphics or image particular to the graphics commands, the specific graphics commands must be resent.
In certain situations, graphics commands are optimized or compressed. This optimization or compression typically is performed in trans-machine implementations, such as terminal-service systems, where communication between a central server computer and remote client computers is through a communications medium such as a network. Bandwidth over the communication medium or network is often limited. Therefore, optimization or compression may be needed. Optimization or compression may result in compromised image quality. For example, in certain situations, it is desirable to magnify the graphic or image at the receiving computer or device; however, since the graphics commands have been compressed, magnification may result in image degradation.
Furthermore, in certain cases, different applications may support or provide different types or dissimilar graphics commands. For example, one application may support a legacy graphics command format such as GDI, while another application may support a new or different graphics command format. However, it may be desirable to support different graphics command formats and allow graphics to be processed from applications using different graphics command formats.